Handling corrosive fluids, that is, corrosive liquids and/or gases, has been a serious problem for the petroleum and chemical industries almost from the founding of these industries. This problem is increasing, particularly in the petroleum industry since much of the world's recoverable hydrocarbons are in the form that is frequently referred to as "sour crude". That is, crude oil that is inheritantly corrosive. The chemical industry encounters similar problems in treating, processing and storing corrosive liquids and gases. The production of crude oil from a subterranean formation to the earth's surface, the transport of crude oil from a producing well to a storage facility and from a storage facility to a refinery frequently involves movement of fluid through pipes. The same occurs in the chemical industry in that piping is an essential part of chemical processing facilities.
While piping can be made entirely of corrosion resistant materials, such as plastics and fiberglass, much of the petroleum and chemical industry requires piping that must withstand higher pressures and more tensile strength that is available with plastics or fiberglass. Accordingly, much of the piping utilized in the petroleum and chemical industries is formed of metal. Steel obviously is the most common metal used in manufacturing pipes because of its high strength, machinability, economy and ready availability. While steel has many important attributes that recommend it for high strength or high pressure piping, it has the serious limitation that steel is readily attacked by many, if not most, corrosive liquids and gases. Accordingly, much effort has gone into devising methods of manufacturing high strength and high pressure resistant piping utilizing steel as an outer core with an inner core formed of a corrosion resistant alloy. Such piping takes advantage of the strength and relative economy of steel with the advantage of a corrosion resistant internally clad alloy that enables piping to transport corrosive, liquids or gases without the corrosive components attacking the piping outer steel shell.
A method of manufacturing an internally clad tubular product is described in detail in co-pending U.S. patent application Ser. No. 08/939,305 entitled "An Improved Method is of Manufacturing An Internally Clad Tubular Product". For additional background information relating to internally clad metallic tubular products, see U.S. Pat. No. 4,620,660 entitled "Method of Manufacturing An Internally Clad Tubular Product" that issued on Nov. 4, 1986 and U.S. Pat. No. 4,744,504 entitled "Method of Manufacturing A Clad Tubular Product By Extrusion" that issued on May 17, 1988. Each of these are incorporated herein by reference.
The techniques detailed in the two previously issued patents and the pending application referenced above provide for manufacturing internally clad tubular products. However, a tubular clad pipe to be successfully utilized must be used in a system that provides for means of coupling lengths of pipe together to take advantage of the internal corrosion resistant cladding of the pipes. This is the subject of this disclosure, that is, this invention provides an improved corrosion resistant tubular system that employs internally clad tubular pipes and internally clad couplings.